Centrifugal casting device



June 3, 1958 A. BlGANzoLl CENTRIFUGAL CASTING DEVICE Filed June 13, 1957 v A w .Inl w United States Patent O CENTRIFUGAL CASTING DEVICE Alexandre Biganzoli, Fumel, France, assigner to Cornpagnie de Pont-A-Mousson, Nancy, France, a French body corporate Application .lune 13, 1957, Serial No. 665,461

Claims priority, application France June 16, 1956 9 Claims. (Cl. 22-65) The present invention relates to rotatable, metallic, tubular, casting devices used in machines for centrifugal casting pipes and the like.

It is known that in this casting method there is used a rotatable casting device formed of the combination of a mould or shell, and an o-uter reinforcing sleeve which acts as a support for the shell and rolls along rollers, means being provided for circulating cooling uid between the sleeve and the shell.

ln view of the high rotational speed of the unit, which speed is the higher as the diameter of the shells is smaller, it is essential that the shell and sleeve remain exactly concentric. Whatever the means used for obtaining this centering, it should be observed that, owing to the heating of the shells due to contact with the molten metal, radial and longitudinal expansions occur (for example, the longitudinal expansion could amount to several centmetros for a shell 6 metres long). Thus the centering means used must be capable of accommodating the expansion of the shell while holding it perfectly both in the cold and hot state.

The object of the invention is to provide a casting device for centrifugal casting having a concentric shell and sleeve between which there is formed an annular space. This device is characterized in that there are disposed between the shell and the sleeve in said annular space a plurality of closed elastic collars arranged in spaced relation along the shell, each of these collars being formed of a helical spring which is bent in the form of a ring around the shell, the coils of the spring being open or in non-abutting relation and the two ends of the spring being interconnected by fastening means and/ or welding.

Owing to this new application of helical springs, the applicant has found that the centering of the shell in the sleeve is absolutely perfect, irrespective of variations in the dimensions of the shell due to thermal expansions in the course of machine operation.

Preferably, the shell and the sleeve are rigidly interconnected at one of their ends, whereas the other ends are independent, as known per se, and the helical springs are spaced a constant distance apart.

Further features and advantages of the invention will be apparent from the ensuing description with reference to the accompanying drawing, to which the invention is in no way limited.

Fig. l is a diagrammatic longitudinal sectional View of a device embodying the invention;

Pig. 2 is a cross-sectional View taken along line 2 2 of Fig. l;

Fig. 3 is a View of one of the springs before it has been bent into the form of a collar, and

Fig, 4 is a sectional view on an enlarged scale of one of the collars mounted on the shell.

In the embodiment shown in the figures a sleeve 1 is supported by rollers 2 rotatably mounted in supports 3 rigid with the stand of the machine (not shown). The sleeve 1 is rotated by amotor (not shown).

Disposed inside the sleeve, is a shell 4 forming a ICC mould fixed at one end to the sleeve 1 by bolts 5. The outside diameter of the shell is less than the inside diamter of the sleeve, so that an annular space is formed therebetween. According to the invention, there are disposed in this free space between the sleeve and shell in equi-spaced relation along the shell, collars 6 each of which is formed by a helical spring 6a (Fig. 3) which is wound round the shell so as to form a ring, the two ends 7@ of the spring 6a being interconnected at 9 by welding and/ or fastening means, such as clips.

To facilitate the positioning of the collars 6 along the shell, annular recesses 10 are formed on the outer face of the shell in regions where the collars are to be placed. These recesses 10 (Fig. 4) are shallow, that is about 1 to 2 mm. deep, and are defined laterally by sides 11, 12, for example chamfered at 45.

Preferably, the springs 6a forming the collars 6 are mounted on the shell with a slight tension of about 1%; in other words, the length of the inner circumference of the collar, in the free state, is about 99% of the circumference of the recess 10.

As the collars 6 are disposed on the shell 4, the inside diameter of the sleeve l must be equal to or preferably very slightly less than (a few tenths of a millimetre) the outside diameter of the collars.

The number of collars required to hold the shell in position must be such that the shell is suliciently supported throughout its length. The last collar 6b adjacent the free end of the shell, that is the region thereof which undergoes the greatest longitudinal displacement under the effect of thermal expansion, is of course disposed such distance a from the end 13 of the sleeve that, having regard to the longitudinal expansion of the shell 4, the collar 6b does not move out of the sleeve when the shell has reached its maximum expansion. For example, in the case of a shell 6 metres long and having an outside diameter of about mm., the distance between the collars could be about 1 metre. The collars consist of helical springs formed from a 3 mm. diameter wire the outside diameter d being about l5 mm. and the pitch p between the coils being about l2 mm. The width of the base of the recess 10 formed in the shell 4 for receiving the collar has about the same dimension as the diameter d of the spring 6a (Fig. 4).

Owing to this manner of mounting the shell in the sleeve, it has been found that the centering afforded by the springs is absolutely perfect when the shell is cold or hot after expansion, especially radial expansion.

During the expansions, and on account of the ready deformation of the collars 6, there is substantially no compressive force exerted on the shell and any deformation of the latter is avoided.

It should be observed, moreover, that the shell is particularly easy to mount in the sleeve. With the shell 4 disposed in front of the entrance to the sleeve 1 (at the left of the sleeve as viewed in Fig. l), the number of collars 6 required for centering are rst placed on the shell. Owing to the low tension of the collars on the shell, they are very easily placed in position and rolled along the shell. The shell provided with the collars is then introduced into the sleeve. As the diameter of the sleeve is equal to or preferably only very slightly less than (some tenths of a millimetre) the outside diameter of the collars, introduction of the shell into the sleeve requires practically no force. Thereafter, the shell is merely secured to the sleeve by the bolts 5.

Although a specific embodiment of the invention has been described, many modiiications and changes may be made therein without departing from the scope of the invention as defined in the appended claims.

aeaeaea Having described my invention what-I claim as new and desire to secure by Letters Patent is: I

1. A device for centrifugal casting comprising a sleeve, a'shell disposed in said sleeve and constituting a mould whose outside diameter is less than the inside diameter of said sleeve so as to provide an annular space between said Y sleeven and said V,shell over substantially the whole of their length, and a plurality of elastic collars disposed in'spaced relation along Vsaid shell inA said annular space for maintainingvsaid shell in coaxial relation to said sleeve, each of said collars being formed of a helical spring which is bent in the form of a ringY around said shell, the two ends ofthe spring being interconnected and the coils of the spring being manon-abutting relation'to one another.

2. A` device as claimed in claim 1, wherein the two endsof said spring are interconnected by hooking means. 3. A .deviceV as'claimed in claim 1, wherein the Ytwo ends of vsaid'spring Vareinterconnected by welding.

' 4. A devicey as claimed in `claim l, wherein said shell and Vsaid sleevev are rigidlysecured to one another at oneV of their ends whereas the other ends are independent, said collarsV being spaced apart,

' diameter of Ysaidtcollars is equal to atleast along said YshellY at equal distances Vv5. A device as claimed inclaim 1, wherein the outer face of said shell comprises peripheral shallow annular recesses in each of which one of said collars is disposed and thus held in position longitudinally of the shell. n

6. A device as claimed in claim 5, wherein each of said recesses has chamfered sides.

7. A device as claimed in claim 1, wherein the inside diameter of Veach of said collars is about 99% of the ont-Y side diameter of the portion of the outer Vface of the shell References Cited in the l'e of this patent UNITED STATES PATENTS 1,573,089 Rice .Q. Feb. 16, 1926 2,487,424

Cavallier Nov. 8, 1949 

